Problem and Advice of Isohumic Property in Chinese Soil Taxonomy

The Isohumsols in Chinese soil taxonomy use the Isohumic property as differentiating characteristics.However,through 172 soil pedon which have mollic epipedon and accord with criterion of mollisols in US soil taxonomy,there are 46 pedon without Isohumic property(Rh value0.4),occupy 26.7%,most of them are in Heilongjiang,caused by the richer humus in top soil layer,on account of the land cultivated lately,and have cryic temperature regime.Those mollisols(Rh0.4) included in Cambisols,this is a problems be worth discussing.